The invention relates to an energy recovering equipment as well as to a method for recovering an energy by means of an energy recovering equipment in accordance with the preamble of the independent claims.
These days, there are a lot of projects that can help meet the increasing demand for clean, renewable electrical energy and can help reduce reliance on fossil fuels always associated with greenhouse gas emissions. As a result, in particular the importance of solar power is steadily increasing.
Beside a lot of well known techniques for changing solar power into electric energy, there are solutions proposed that use a concentrating solar power technology, wherein the used equipments have an integral storage system for storing or buffering the collected solar power in form of thermal energy. The aforementioned technology generates power from sunlight by focusing the light energy of the sunlight from a field of sun-tracking mirrors, also called “heliostats”, onto a central light or radiation receiver, which is installed on a respective central tower. Because of its high melting point, its relatively high heat capacity and its highly efficient heat transfer properties, liquid salt, which flows similar to water when melted, is circulated through the receiver, collecting the energy gathered from the sun. The heated salt is then fed to a heat insulated storage tank where it can be stored for a considerable period of time with minimal energy losses. When electricity is needed and, thus, to be generated, the hot melted salt is routed from the storage tank to a heat exchanger to produce steam being used to generate electricity using a conventional steam turbine equipment. The still liquid but considerable cooled salt is then sent to the cold salt storage tank back, ready to be reused and reheated by the sun in an other new solar energy gathering cycle.
The advantages of the aforementioned technology are obvious. It stores solar energy for use on demand and establishes a stable electricity supply reducing grid reliability impacts from other intermittent renewable energy sources. What is more, if needed, the stored energy in the molten salt can be used to produce electricity even when there is no sunlight. This is particularly beneficial for places where peak electricity demand can continue after the sun goes down and other solar resources can no longer operate, for example solar energy sources such as conventional photovoltaic cells. In addition, the liquid salt provides a cost-effective way to store the solar energy due to its highly efficient heat transfer properties. No natural gas, oil, wood or other fuels are involved in this energy producing process and, as a result, associated combustion emissions to maintain operating stability as some other solar technologies do, can be completely avoided.
However, a still unsolved serious problem is the relatively high power consumption of the pumping system that is used for pumping the liquid salt through the receiver cycle, in particular for pumping the relatively cold liquid salt up to the receiver which is located onto the receiver tower, for example about 200 m high.